package test;
import java.util.Scanner;
public class fr {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        //在此输入您的代码...
        char[] a = {'A','B','C','D','E','F'};
        boolean[] flag = new boolean[6];
        for(int i = 0;i<6;i++){
            int sum=0;
            char xf = a[i];
            if( xf!='A'){
                sum+=1;
            }
            if( xf=='A'||xf=='C'){
                sum+=1;

            }
            if( xf=='A'&& !(xf=='A'||xf=='C')){
                sum+=1;
            }
            if( !(xf=='A'&& !(xf=='A'||xf=='C')) && xf!='F'){
                sum+=1;
            }
            if( xf!='A' && !(xf=='A'&& !(xf=='A'||xf=='C')) && xf!='F' && sum==2){
                sum+=1;
            }
            if(xf=='F'){
                sum+=1;
            }
            if (sum==3){
                    flag[i]=true;
                }
            }
        for(int j=0;j<6;j++){
            if(flag[j]){
                System.out.println(a[j]);
            }
        }
        scan.close();
    }
}
